Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
  • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
  • C08F20/52—Amides or imides
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/74—Synthetic polymeric materials
  • A61K31/785—Polymers containing nitrogen
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P3/00—Drugs for disorders of the metabolism
  • A61P3/12—Drugs for disorders of the metabolism for electrolyte homeostasis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P39/00—General protective or antinoxious agents
  • A61P39/04—Chelating agents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F26/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
  • C08F26/02—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a single or double bond to nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0025—Crosslinking or vulcanising agents; including accelerators
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
  • C08K5/41—Compounds containing sulfur bound to oxygen
  • C08K5/42—Sulfonic acids; Derivatives thereof

Definitions

• the present invention relates to a process for the preparation of cross-linked polyallylamines or pharmaceutically acceptable salts thereof.
• the invention also relates to a process for the preparation of Sevelamer, or pharmaceutically acceptable salts thereof, preferably hydrochloride or carbonate salts, used in the treatment of hyperphosphatemia, and having good flowability, low porosity and/or a swelling index of between 7 and 9.
• Hyperphosphatemia often accompanies diseases connected with renal insufficiency which is an ever more widespread chronic condition associated with a progressive loss of kidney function which often complicates the course of other diseases such as diabetes and cardiovascular diseases. Particularly when it is present for long periods of time, hyperphosphatemia leads to serious anomalies in the metabolism of phosphorus and calcium, causing calcification of the soft tissues, for example, joints, lungs, eyes, vessels, arteries, etc.
• Hyperphosphatemia is generally treated with phosphate group binders such as anion-exchange polymers. These polymers lead to a reduction in the blood phosphate level without increasing the absorption of other clinically undesirable compounds.
• Cross-linked polyallylamines Sevelamer for example, are amongst the anion-exchange polymers that are used widely in the treatment of hyperphosphatemia. Sevelamer, which is polyallylamine cross-linked with epichlorohydrin, was marketed initially as the hydrochloride and more recently, as the carbonate. Sevelamer carbonate has similar efficacy to Sevelamer hydrochloride but is better tolerated by patients.
• Sevelamer is a compound of structural formula (I), and empirical formula (Ia): [ (C 3 H 7 N) a+b ⁇ (C 9 H 17 N 2 O) c ] m in which:
• EP716606B1 describes the preparation of Sevelamer hydrochloride by the polymerization of allylamine in the presence of an initiator, and subsequent cross-linking with epichlorohydrin.
• European patent EP1175451B1 describes the preparation of Sevelamer by the reaction of polyallylamine and a cross-linking agent such as epichlorohydrin or 1,3-dichloro-2-propanol, in a basic environment, in water and in a water-miscible solvent.
• a cross-linking agent such as epichlorohydrin or 1,3-dichloro-2-propanol
• Patent application WO2009/010531 describes the preparation of Sevelamer by the reaction of allylamine with 1,3-bis-allylamino-2-propanol as cross-linking agent.
• Patent application WO2009/125433 describes the preparation of Sevelamer carbonate by cross-linking of polyallylamine carbonate with epichlorohydrin, optionally in the presence of an emulsifier and/or surfactant.
• Polyallylamine carbonate is obtained by basic treatment of polyallylamine hydrochloride and subsequent reaction with a carbonate source.
• Patent application WO2001/18073 describes the preparation of Sevelamer with low cohesiveness which is achieved only after several steps which provide for the reaction of an aqueous polyallylamine solution with a cross-linking agent such as epichlorohydrin, washing of the aqueous solution with an alcohol/water solution in the presence of a surfactant, drying of the cross-linked polymer, grinding, and finally sieving.
• a cross-linking agent such as epichlorohydrin
• Patent application WO 01/05408 describes the reaction of polyallylamines with "modifying agents" for the preparation of polyallylamine derivatives in which the nitrogen atoms of the amine groups are bound to hydrophobic substituents of the modifying agents.
• WO 01/05408 describes the use of glycidol as modifying agent. The reaction of the polyallylamine with glycidol does not, however, enable it to be cross-linked, as shown in Comparative Example 6 of the present application.
• cross-linked polyallylamines or pharmaceutically acceptable salts thereof can be produced by a simple process that can be used at an industrial level to produce large quantities of product without the use of toxic reagents and without further process steps.
• the present invention thus relates to a process for the preparation of cross-linked polyallylamines or pharmaceutically acceptable salts thereof which comprises the following steps:
• a further aspect of the present invention relates to the preparation of Sevelamer, or pharmaceutically acceptable salts thereof, preferably hydrochloride or carbonate salts.
• a subject of the present invention is Sevelamer or pharmaceutically acceptable salts thereof, preferably hydrochloride or carbonate salts, obtainable by the above-mentioned process and, in particular, Sevelamer or pharmaceutically acceptable salts thereof, preferably hydrochloride or carbonate salts, having an angle of rest of between 25.0° and 27.0° and/or a true density of between 1.25 and 1.32 and/or a swelling index of between 7 and 9.
• polymer refers not only to a homopolymer but also to a copolymer.
• polyallylamine refers to a polymer which comprises allylamine as a repetitive unit.
• repeating unit refers to a part of the polymer chain which is derived from a single molecule of a monomer.
• cross-linked refers to interconnections between the polymer chains.
• cross-linking agent refers to an agent which brings about cross-linking, branching, or a combination thereof.
• C 1 -C 6 alkyl refers to a branched or linear hydrocarbon containing from 1 to 6 carbon atoms.
• Examples of C 1 -C 6 alkyl groups include but are not limited to methyl, ethyl, n -propyl, isopropyl, n -butyl, sec- butyl, isobutyl, tert -butyl, n -pentyl, n -hexyl.
• the C 1 -C 6 alkyl may optionally be substituted with one or more electron-attractor groups.
• aryl refers to an aromatic carbo-cycle constituted by 1 or 2 rings fused or bound together by a single bond.
• aryl groups include but are not limited to phenyl, and ⁇ - or ⁇ -naphthyl.
• the aryl group may optionally be substituted with one or more C 1 -C 6 alkyl groups e/o electron-attractor groups.
• electron-attractor group refers to a group which tends to stabilize carbanions by helping to disperse their negative charge.
• electron-attractor groups include but are not limited to, halogens, such as fluoro, chloro, bromo, iodo groups; the nitro group (NO 2 ); and the nitrile group (CN).
• pharmaceutically acceptable salts refers to nontoxic inorganic or organic salts.
• examples of pharmaceutically acceptable salts include but are not limited to: carbonate, hydrochloride, hydrobromide, sulphate, hydrogen sulphate, citrate, maleate, fumarate, trifluoroacetate, 2-naphthalenesulphonate, and paratoluenesulphonate. Further information on pharmaceutically acceptable salts can be found in pharmaceutical chemistry manuals, for example: Handbook of pharmaceutical salts, P. Stahl, C. Wermuth, WILEY-VCH (Eds., 2008, pp. 127-133 ).
• one pot refers to two or more consecutive reactions which are carried out without isolating the respective intermediate product or products.
• the present invention relates to a process for the preparation of cross-linked polyallylamines or pharmaceutically acceptable salts thereof which comprises the following steps:
• a further aspect of the present invention relates to the preparation of Sevelamer, or pharmaceutically acceptable salts thereof, preferably hydrochloride or carbonate salts.
• Another aspect of the present invention relates to Sevelamer or pharmaceutically acceptable salts thereof, preferably hydrochloride or carbonate salts, obtainable by the process of the present invention and preferably having an angle of rest of between 25.0° and 27.0° and/or a true density of between 1.25 and 1.32 and/or a swelling index of between 7 and 9.
• steps a), b), c) and d) of the process of the present invention are carried out in "one pot".
• the allylamine of formula (II) is polymerized in the presence of a radical initiator in an acid environment in a polar solvent or a mixture of polar solvents.
• the radical initiator is preferably selected from nitrogenous compounds, more preferably azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, or 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (VA-044); organic peroxides, more preferably benzoyl peroxide, di-tert-amyl peroxide, dicumyl peroxide, isopropylbenzene peroxide; inorganic peroxides, more preferably hydrogen peroxide, sodium peroxide, or potassium peroxide; compounds that can be activated by thermal or redox reactions, or a combination thereof; more preferably, the radical initiator is a nitrogenous compound, even more preferably 2,2'-azobis(2-amidinopropane) dihydrochloride o 2,2'-azobis[2-(2-imidazolin-2
• the molar ratio of allylamine to radical initiator is preferably between 20:1 and 50:1, more preferably between 20:1 and 35:1.
• the polymerization reaction of step a) is performed in the presence of an acid.
• the acid is preferably an inorganic acid, more preferably hydrochloric acid, hydrobromic acid, sulphuric acid, nitric acid, phosphoric acid, or the like. Even more preferably, it is hydrochloric acid.
• the polar solvent is preferably selected from water; an ester, more preferably ethyl acetate or butyl acetate; a nitrile, more preferably acetonitrile; an ether, more preferably tetrahydrofuran or dioxane; an amide, more preferably dimethylformamide or dimethylacetamide; a sulphoxide, more preferably dimethylsulphoxide, or mixtures thereof, even more preferably water.
• the polymerization reaction is performed at a temperature such that the reaction goes to completion, preferably at a temperature between the decomposition temperature of the radical initiator and the reflux temperature of the reaction mixture, more preferably between 60 and 80°C.
• the polyallylamine thus obtained can be isolated by separation techniques well known to persons skilled in the art, such as: extraction, filtration, crystallization, precipitation, and the like, or it may be used directly, without isolation or purification, in the subsequent cross-linking step b).
• the polyallylamine is preferably not isolated.
• the polyallylamine is reacted with the cross-linking agent of formula (III) in which R is a C 1 -C 6 alkyl group, or an aryl group optionally substituted with one or more alkyl groups and/or electron-attractor groups.
• R is selected from methyl, trifluoromethyl, p -tolyl, and m -nitro-phenyl; more preferably m -nitro-phenyl or p -tolyl.
• the cross-linking agent of formula (III) is preferably m -nitrobenzensulphonyl glycidol or tosyl glycidol.
• the cross-linking reaction of step b) is performed in the presence of a base.
• a base Any base known to persons skilled in the art may be used in the present invention to bring the pH of the solution to basic values.
• the base is an inorganic base, more preferably sodium or potassium hydroxide or sodium or potassium carbonate, even more preferably sodium hydroxide.
• the cross-linking agent of formula (III), in solid form or in solution, is added to the polyallylamine solution.
• Any polar solvent or mixture of polar solvents known to persons skilled in the art may be used in the present invention.
• the compound of formula (III) is used in solution in a polar solvent, more preferably water, even more preferably ethyl acetate.
• the concentration of the cross-linking agent of formula (III) is preferably between 0.5 and 2 mol/l, more preferably between 1.2 and 1.8 mol/l.
• the cross-linking agent of formula (III) may be prepared by any method known to persons skilled in the art, for example, as described in J. Org. Chem., 1989, 54, 1295-1304 .
• the compound of formula (III) may be prepared as shown by way of example in Scheme 1, by reacting the glycidol of formula (IV), which is a commercial product, with the sulphonyl halide R-SO 2 X of formula (V) in which R has the meaning defined above and X is a halogen, for example, chlorine, bromine, or iodine.
• the reaction takes place in a basic environment, preferably with the use of an organic base such as an amine, for example, triethylamine or diisopropylethylamine; an amidine, for example, 1,8-diazadicyclo[5,4,0]undec-7-ene; or an aromatic base, for example, pyridine. More preferably, the base is triethylamine or diisopropylethylamine.
• an organic base such as an amine, for example, triethylamine or diisopropylethylamine
• an amidine for example, 1,8-diazadicyclo[5,4,0]undec-7-ene
• an aromatic base for example, pyridine.
• the base is triethylamine or diisopropylethylamine.
• the compound of formula (III) may be isolated in accordance with techniques well known to persons skilled in the art such as, for example, extraction, filtration, crystallization, precipitation, and the like, or may be used without further separation and purification, by adding the solution containing it directly to the polyallylamine mixture.
• the reaction mixture is preferably stirred for 6-14 hours, more preferably 10-12 hours. An easily handled, solid polymer is obtained.
• the reaction mixture is then brought to acid pH by the addition of an acid to give the salified polymer.
• any acid known to persons skilled in the art may be used in the present invention to salify the polymer.
• the acid is a pharmaceutically acceptable acid, more preferably an inorganic acid, even more preferably hydrochloric acid.
• the salified polymer can be isolated by techniques known to persons skilled in the art, such as precipitation, filtration, with or without pressure and/or under vacuum, crystallization, centrifuging, decantation, and the like.
• the salified polymer is a hydrochloride or a carbonate, more preferably a carbonate.
• the polymer hydrochloride is converted into the corresponding carbonate by reaction with a carbonate source.
• a carbonate source for example, sodium or potassium carbonate, preferably sodium carbonate
• the reaction mixture is brought to a suitable temperature between room temperature and the reflux temperature of the reaction mixture, preferably between room temperature and 40°C.
• the polymer in the form of the carbonate salt is separated from the mother liquor, washed and dehydrated.
• the process of the present invention permits the preparation of cross-linked polyallylamines or pharmaceutically acceptable salts thereof, preferably Sevelamer or pharmaceutically acceptable salts thereof, more preferably hydrochloride or carbonate salts, even more preferably the carbonate salt.
• the process of the present invention is an efficient, inexpensive process with good yields, is repeatable, and takes place in very mild conditions without the use of surfactants and/or toxic substances.
• the process of the present invention can easily be used on an industrial scale to prepare large quantities of product and enables the final product to be produced with well-defined chemical and physical characteristics which lead to easy handling of the solid obtained, without the need for further processes such as grinding, lyophilization, or spray-drying.
• Sevelamer and the pharmaceutically acceptable salts thereof such as the hydrochloride and carbonate salts which can be obtained by the process of the present invention have good flowability, good porosity, and/or a swelling index of between 7 and 9.
• the flowability of a powder is determined by measurement of the corresponding angle of rest.
• the angle of rest measured on Sevelamer or the pharmaceutically acceptable salts thereof that are obtained by the process described in the present invention is between 25.0° and 27.0°.
• the angle of rest was measured in accordance with the method described in European Pharmacopoeia 6.0 (2010); 100 g of product were introduced into a hopper having a blocked hole placed 10cm from a surface. The hole was opened, the powder was allowed to flow out, and the flow time was measured.
• the porosity of a powder is determined by measurement of its true density.
• a high true density indicates low porosity, given that there are fewer empty interstitial spaces.
• Sevelamer and the pharmaceutically acceptable salts thereof such as the hydrochloride and carbonate salts which can be obtained by the process described in the present invention have a true density of between 1.25 and 1.32.
• the true density was measured in accordance with the helium pycnometry method as described in the ASTM B923-02 " Standard Test Method for Metal Powder Skeletal Density by Helium or Nitrogen Pycnometry".
• Sevelamer and the pharmaceutically acceptable salts thereof such as the hydrochloride and carbonate salts which can be obtained by the process described in the present invention have a swelling index of between 7 and 9.
• a high swelling index means that the polymer incorporates water until it adopts a volume equal to the value of the index.
• the swelling index was measured in accordance with the procedure described in patent WO 01/18073 which is incorporated herein by reference.
• the phosphate sequestering power of Sevelamer and the pharmaceutically acceptable salts thereof such as the hydrochloride and carbonate salts which can be obtained by the process described in the present invention is between 5.0 and 6.0 mmol/g.
• the allylamine polymerization reaction is performed with the use, as radical initiator, of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (VA-044) in a molar ratio of allylamine to radical initiator of approximately 23 : 1 and hydrochloric acid as the acid.
• the polar solvent used is water.
• the polymerization reaction is performed at a temperature of 30-50° C, preferably approximately 40°C.
• the reaction for the cross-linking of the polyallylamine thus obtained is performed in a basic environment by the addition of sodium hydroxide and one of the cross-linking agents of formula (IIIa) or (IIIb) given below, that is, tosyl glycidol or m-nitrobenzensulphonyl glycidol, respectively, in ethyl acetate.
• the reaction takes approximately 10-12 hours.
• the pH is then brought to acidity by the addition of hydrochloric acid.
• the solid thus obtained which corresponds to Sevelamer hydrochloride, is suspended in water and sodium carbonate is added. The temperature is brought to approximately 30-35°C. After washing with isopropanol, Sevelamer carbonate is obtained.
• 37% HCl 38 g, 0.385 mol was introduced into a 250 ml, 4-necked flask with a mechanical stirrer, cooler, and thermometer and diluted with water (24 ml). The temperature was brought to 2-4°C and allylamine (20 g, 0.35 mol) was added dropwise. Upon completion of the dropwise addition, the temperature was brought to 72-73°C. During the heating, at approximately 40°C, the VA-044 initiator (4.8 g, 0.015 mol) was added. The mixture was left to react for 4h. The aqueous solution was clear and the viscosity increased over time.
• the solution was brought to pH 10 with 50% NaOH and the solution of tosyl glycidol (IIIa) in AcOEt (20 g, 0.0877 mol in 50 ml) was added dropwise. The addition was performed over a period of 1 hour. The mixture was left to react overnight and a gelatinized product was obtained. Further AcOEt (80 ml) was added. The mixture was brought to acid pH with 37% HCl and filtered through cloth. The solid was washed with a water/isopropanol mixture (2 x 250 ml) and with isopropanol (2 x 250 ml). 50 g of a moist solid was obtained. The solid was dried in an oven to give 38 g of still moist Sevelamer hydrochloride which was used unchanged in the next step.
• Sevelamer hydrochloride 28 g was suspended in water (420 ml). Sodium carbonate (17.5 g, 0.165 mol) was added during stirring. The temperature was brought to 30-35°C and stirring was continued for approximately 30 minutes. 200 ml of isopropanol was added and the mixture was filtered in a Buchner filter. The solid was washed with a (1:1) water/isopropanol mixture (2 x 250 ml) and with isopropanol (250 ml). 35 g of a moist solid was obtained. The product was dried in an oven under vacuum giving 16 g of Sevelamer carbonate.
• 37% HCl (4.8 g, 0.0487 mol) was introduced into a 3-necked, 50 ml flask with a magnetic stirrer, cooler, and thermometer and was diluted with H 2 O (2 ml). The temperature was brought to 2-4°C and allylamine (2.53 g, 0.0443 mol) was added dropwise. Upon completion of the dropwise addition, the temperature was brought to 72-73°C. During the heating, at approximately 40°C, the VA-044 initiator (0.62 g, 0.0019 mol) was added. The mixture was left to react for 4h. The aqueous solution was clear and the viscosity increased over time.
• the solution was brought to pH 10 with 50% NaOH and the solution of glycidol in AcOEt (1.61 g, 0.0218 mol in 12.5 ml) was added dropwise. The addition was carried out over a period of 1 hour. The mixture was left to react overnight and the formation of Sevelamer was not noted since an emulsion was obtained which, upon the addition of water, gave rise to a clear, and hence polymer-free, solution.

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